After closing out Dallas in the final two games of the second-round series without being whistled for a penalty, the Blues had two defensemen (Jay Bouwmeester, Colton Parayko) serving time in the box Saturday when the Sharks scored the game’s biggest goal on a 5-on-3 power play. Joe Pavelski’s score put the Sharks in front 2-1 shortly after the Blues had quieted things down with a tying goal. The Blues were left to chase the game after failing to kill off an extended PP.

2. Mental errors can be just as damaging — more harmful, actually — than physical mistakes.

3. If your special teams continue to be embarrassingly and mystifyingly awful — you will be vulnerable. And at risk of undoing your quality work in other areas.

As I’ve written approximately 500 times this season, 5-on-5 strength is the Blues’ foundation — and a winning foundation at that. But their special teams have been an abject failure since the start of the second round.

Since the start of the seven-game series vs. Dallas, and including Game 1 at San Jose, the Blues have converted 2 of 23 power-play opportunities. That’s 8.7 percent. And that’s pathetic. Since Game 1 of the Dallas series, the Blues are 1 for 21 on the PP, for 4.7 percent. And their penalty killing is somewhere between terrible and mediocre. The Blues have snuffed only 72 percent of opponents’ power plays since the start of the second round.

4. At some point your best players and most lethal snipers have to alter games and outcomes by making high-impact plays and scoring big goals.

The Sharks presented evidence in support of this theory with the imposing presence of their top line: game-breaking center Logan Couture and wingers Gus Nyquist and Timo Meier.

The trio combined for four goals and four assists overall. During 10 minutes and 30 seconds of 5-on-5 action, the Couture line outscored the Blues 2-0 and had a 64.6 Corsi possession rating. (Fifty percent is average.)

Meanwhile, on the Blues’ side, two names in particular jump out…

In 217 minutes and 42 seconds of 5-on-5 hockey spread over 14 games, Vladimir Tarasenko has one goal and an assist.

In 223 minutes and 13 seconds at 5-on-5, Brayden Schenn has one goal and an assist.

One goal.

Uno.

The same number as forwards Sammy Blais, Robby Fabbri, Alex Steen and Oskar Sundqvist. The same number as defenseman Edmundson and Vince Dunn. And one fewer goal than another defenseman, Mr. Pietrangelo.

Tarasenko is a minus 8 even strength during the postseason, the worst among all players on the four remaining teams. Ryan O’Reilly and Schenn aren’t much better at minus 5.

Enough. Let’s go.

Tarasenko’s body language was terrible during Game 1 … and that bugs even me, a known Tarasenko apologist.

@ The Blues had a Corsi possession rating of 54.2 percent compared to San Jose’s 45.8. That’s a significant edge.

@ The Blues had a 57.1 percent share of the shots on goal at 5-on-5.

@Also at 5-on-5: the Blues had a 25-19 edge over the Sharks in scoring chances.
Same with high-danger chances from the slot and crease: 14 for St. Louis, 9 for San Jose.

But …

At 5-on-5 San Jose outscored the Blues 4-3. In other words this game shouldn’t have been a three-goal blowout. The Blues’ lack of discipline led to the game-changing Sharks’ power play.

And because of the Blues’ silly mental mistakes and their gift of gooey buttercake turnovers, the Sharks feasted on easier scoring chances. So easy that one of the home team’s goals went off Edmundson and into the net.

If the Sharks had easier chances — which, by the way, is backed up by the numbers on average shot distance — the Blues actually had more chances at 5-on-5.

To use a baseball analogy: the Blues left too many runners in scoring position.

This isn’t absolute, of course. The Blues’ first-period penalties and lapses in attention cost them dearly. But the Blues played their worst 5-on-5 hockey — strength of structure, strength of possession — in the second period.

Over those 20 minutes the Blues had a weak Corsi of 44.8 percent, and San Jose had a 62.5 percent share of the scoring chances. Not surprisingly the Blues were outscored 3-1 in the second period during 5-on-5.

The Blues relocated their game and necessary style of play in the third period. They turned up the intensity, got on the puck, stayed on the puck, and generated a 70.6 percent Corsi rating with an 83.3 percent share of shots.

The Blues “won” that period, 1-0 at 5-on-5. But the one goal was insufficient; such possession dominance must be cashed in for more than a single goal.

Perhaps the Blues’ third-period surge was attributable to a San Jose letdown. That’s one view.

Or maybe the third period offered a demonstration of the Blues making corrections and adjustments and shaping up their game in advance of Game 2.

I suppose we’ll find out Monday night when the puck drops at the Shark Tank.

LOOKING AHEAD TO GAME 2

With the Blues down 1-0 in a best-of-7 series for the first time this postseason, we look forward to seeing how they handle the situation. I trust that the initial response will be emphatic, but this is all about winning the game.

As I mentioned earlier … despite so many things going on tilt for the Blues, they were outscored 4-3 at 5-on-5 … which shows there isn’t much of a gap between the teams despite a rotten day for the Blues, a sunny day for the Sharks and the three-goal difference on the scoreboard.

The leftover happiness/celebration that followed the scintillating Game 7 drama-o-rama vs. Dallas at Enterprise Center came to an abrupt end in the Game 1 debacle at San Jose. It’s time to put away the party hats and get serious about taking on the Sharks — and this time, no gifts should be presented to the home team in Game 2. The Blues can’t afford to be stuck in the fog, making hazy mistakes, for a second consecutive contest.

Since the second week of December, the Blues have responded with admirable consistency to challenges and predicaments. They haven’t been perfect in all of these moments, but ultimately have found their way out of danger. They have a chance to do it again.